Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 41 , Issue 12
Showing 1-18 articles out of 18 articles from the selected issue
  • Kazuhiko Majima, Shigeki Orito, Hiroyasu Mitani
    1977 Volume 41 Issue 12 Pages 1207-1211
    Published: 1977
    Released: April 04, 2008
    The lattice diffusion and the grain boundary diffusion of copper in γ-iron were measured in the temperature range from 1105 to 1210°C by the residual activity method with radio-active tracer 64Cu. The experimental penetration profiles were analysed by the instantaneous source model of grain boundary diffusion proposed by Suzuoka. The temperature dependence of the lattice diffusion coefficient D1 and the grain boundary diffusion coefficient Dgb are expressed by the following equations:
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  • Yuko Hanatate, Mitsumasa Yamamoto, Hiroyasu Mitani
    1977 Volume 41 Issue 12 Pages 1211-1216
    Published: 1977
    Released: April 04, 2008
    It has been confirmed previously by the authors that the presence of Ni in the grain boundaries plays an important role in the activated sintering for Fe-Ni powder compacts. However, the grain boundary diffusion of Ni into Fe has not been clarified. In this work, the grain boundary diffusion coefficient of 63Ni in bulk Fe is determined by the use of the residual-activity sectioning method in the temperature range from 1153 to 1287°C. The data obtained are analysed by the theory of grain boundary diffusion based on the instantaneous source model proposed by Suzuoka.
    The results are expressed as follows:
    Volume diffusion: D=1.09exp(−70900⁄RT) cm2/sec.
    Grain boundary diffusion: D′=24.1exp(−42100⁄RT) cm2/sec.
    The Fe-Ni mixed powder compacts at high temperatures are also observed by the use of an electron probe microanalyser, and the observed highly promoted grain boundary diffusion of Ni is confirmed to contribute to the Fe-Ni alloying in the inner part of Fe powder.
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  • Yasuhiko Machida, Tokio Yamadaya, Mitsuru Asanuma
    1977 Volume 41 Issue 12 Pages 1217-1220
    Published: 1977
    Released: April 04, 2008
    A method of storing hydrogen as metal hydride has recently attracted considerable interest and many metal hydrides have been studied for this purpose. However, most of metal hydrides are not suitable because of their low dissociation pressure. In this study, the hydride of TiCr2 base intermetallic compound is found to have a characteristic suitable for storing hydrogen. The studied alloy system is Ti1−xZrxCr2−yMny (0<x<0.4, 0<y<2.0). The alloy samples were prepared by arc melting in argon atmosphere. Crystal structure of prepared samples was confirmed to be C14-type single phase by X-ray analysis. The alloy samples reacted very actively with hydrogen to form hydride at room temperature without any activation treatment. The desorption curve of pressure-composition-temperature isotherm (P-X-T) was measured. At the composition Ti0.8Zr0.2Cr0.8Mn1.2, the dissociation pressure at 293 K was 5 atm and the partial molar enthalpy of hydrogen was determined to be −29 kJ/mol H2 from P-X-T measurement.
    The results of the study are summarized as follows.
    (1) The alloy system Ti1−xZrxCr2−yMny has C14-type crystal structure in the composition range 0<x<0.4, 0<y<2.0.
    (2) The alloy absorbs a large amount of hydrogen to form hydride up to the composition Ti1−xZrxCr2−yMnyH3.
    (3) Dissociation pressure P of this hydride system depends mainly on Zr content x and lnP is propotional to x.
    (4) As the Mn content increases, the plateau region increases, and the dissociation pressure does not change significantly.
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  • Shigeo Zaima, Yuzo Takatsuji, Nobutaka Goto
    1977 Volume 41 Issue 12 Pages 1221-1228
    Published: 1977
    Released: April 04, 2008
    On the JIS aluminium cast alloy 8th class, one of Al-Si alloys, the flank wear of carbide tool is examined and the thin ribbon type deposit on the flank is sought by EPMA with respect to the origin and the mechanism of its growth. The results obtained are as follows.
    As the ribbon type deposit is formed with the flank wear, its formation occurs when the flank wear width reaches about 0.2∼0.3 mm and the cutting temperature arises to about 500°C regardless of the tool material or the cutting speed. The flank wear advances by scratching of Si particls, and Co is removed from the tool surface to the flank deposit with rising cutting temperature under high speed cutting. The tool surfaces are partially destroyed as a result of losing the binder, which accelerate the wear. Ni which is contained in the workpiece is a homologous element and has strong affinity with Co, so that Ni seems to contributes to the removal of Co, and the carbide tool is abrased severely during high speed cutting of the workpiece containing a large amount of Ni. Si particles in the workpiece breaks into fine grains under a high stress condition near the cutting edge, subdivides still more, abrases pulling into and pressing against the tool flank, and hangs down as the ribbon type deposit.
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  • Kiyoshi Kusabiraki, Yutaka Shiraishi
    1977 Volume 41 Issue 12 Pages 1229-1236
    Published: 1977
    Released: April 04, 2008
    In order to obtain the vibrational spectra of high temperature melts such as fused salts and molten slags, improved infrared emission spectrometry was proposed. The feature of this method consists of the combination of two spectra emitted from the thin and the thick layer of samples. The transmission spectrum can readily be derived from the combination of these spectra.
    By the application of this improved infrared emission spectrometry to molten alkaline metal carbonates, distinct spectra could be obtained in the range of wavenumbers between 5000 and 650 cm−1. The obtained results and the suitable structure model of these melts are as follows:
    (1) With decreasing cation size, the frequencies ν3, ν1 and ν4 increase and ν2 decreases.
    (2) With decreasing cation size, the absorption bands become broader. In the case of Li2CO3, the appearance of the forbidden ν1 vibration and the splitting of the doubly degenerated ν3 vibration are significantly observed.
    (3) The anions of Na2CO3, K2CO3 and Rb2CO3 melts have a structure of the nearly plane triangle which belongs to the D3h symmetry.
    (4) In the case of Li2CO3 melt, it is concluded that the structure of anion does not have a D3h but a C2v symmetry, though the possibility of Cs instead of C2v cannot be denied completely, because the strong electric field of the Li+ ion restricts the orientation of Li+ to the carbonate anion and so distorts the anion considerably.
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  • Takayoshi Yoshimori, Norio Katoh, Atsushi Koike
    1977 Volume 41 Issue 12 Pages 1236-1240
    Published: 1977
    Released: April 04, 2008
    Microamounts of carbon (7∼600 ppm) in ferrous and non-ferrous metals and alloys were determined by the combustion-nonaqueous titrimetric method.
    The carbon dioxide liberated by the combustion of a sample was absorbed with dimethyl-formamide (DMF) containing monoethanolamine and then the absorbent was titrated with the standard benzene-methanol solution of tetra-n-butylammonium hydroxide (0.007–0.002 M). The end point of the titration was located either visibly by using thymolphthalein as an indicator or potentiometrically by using a couple of platinum and calomel (containing DMF) electrodes. Pure benzoic acid was used as the standard substance for the standardization.
    Many improvements were given on both the conbustion apparatus and the procedure.
    Microamounts of carbon in various samples were determined by the proposed method. The are: plain carbon and high purity ferritic stainless steels (0.05∼0.002%C), Inconel X-750 (0.027%C), copper alloys (20∼30 ppm C), tantalum powder (40 ppm C) and high purity metallic uranium (7 ppm C). All results were quite satisfactory and indicate that the proposed method was adaptable for the determination of carbon less than 100 ppm in various samples without use of any standard samples or calibration curves.
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  • Yoshinobu Motohashi, Syuichi Otake
    1977 Volume 41 Issue 12 Pages 1240-1248
    Published: 1977
    Released: April 04, 2008
    The elastic energies (E) of edge dislocations in planes of a ⟨111⟩ zone axis which are {pqr}⟨111⟩ type dislocations, and those of edge and screw dislocations with various Burgers vectors in planes {110} and {112} which are {110}⟨lmn⟩ and {112}⟨lmn′⟩ type dislocations in bcc metals (α-Fe, Fe-Si, Nb, V, Ta, W, Mo, Cr, K, Li, Na) are calculated in terms of an anisotropic elasticity theory.
    Among the elastic energies of the {pqr}⟨111⟩ type edge dislocations, the energy of a {112}⟨111⟩ edge dislocation is the maximum and that of a {110}⟨111⟩ edge one is the minimum for all bcc metals evaluated. Among the energies of dislocations with three typical Burgers vectors a⁄2⟨111⟩, a⟨100⟩, and a⟨110⟩ in planes {110} and {112}, the following inequalities hold: Ea⁄2⟨111⟩<Ea⟨100⟩<Ea⟨110⟩ for metals with A>1, where subscripts refer to the Burgers vectors and A is Zener’s anisotropy factor; when A<1, the difference between Ea⁄2⟨111⟩ and Ea⟨100⟩ becomes small, and especially for screw dislocations Ea⟨100⟩ is comparable to Ea⁄2⟨111⟩. According to the analysis of dislocation reactions, it appears that the a⁄2⟨111⟩ and a⟨100⟩ type dislocations are stable and the a⟨110⟩ type is unstable.
    Using these results, the dislocation energies and the choice of the slip system in bcc metals are discussed on the basis of the criterion of the minimum dislocation energy.
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  • Yuzuru Sato, Akira Kojima, Tatsuhiko Ejima
    1977 Volume 41 Issue 12 Pages 1249-1256
    Published: 1977
    Released: April 04, 2008
    Densities and electrical conductivities of NaF-AlF3 binary melts have been measured over the composition range of 0∼30 mol% AlF3 and temperature range up to 1100°C. The density was determined by means of the Archimedian method with two sinkers of different size. For the electrical conductivity measurement, a specially designed conductivity cell made of boron nitride was used.
    The density shows a maximum at the composition of about 20 mol% AlF3. On the other hand, the specific conductivity decreases monotonously with increasing AlF3 content.
    Considering the dissociation of the following scheme,
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    \ oindentAssuming the volume additivity, the dissociation constant, heat of dissociation and molar volumes of Na3AlF6 and NaAlF4 were calculated by means of computer simulation. The values of dissociation constant and heat of dissociation were 0.065 (at 1000°C) and 48.9 kJ/mol, respectively.
    From the conductivity data and the above values, the equivalent conductivity and the activation energy of conductance were determined. Considering the partial ionic dissociation of NaF and conducting species, the mobility of Na+ and the ionic dissociation constant were calculated.
    From these results, it has been discussed how the constituents of NaF-AlF3 melt contribute to the mechanism of electrical conductance.
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  • Shotaro Morozumi, Yutaka Machida
    1977 Volume 41 Issue 12 Pages 1256-1264
    Published: 1977
    Released: April 04, 2008
    Tensile tests in the temperature range of 293 and 573 K and microscopic observations were carried out on vanadium and V-high hydrogen concentration (1240–3410 wt ppm H) alloys. Examining the true stress (σ)-true plastic strain (εp) curves and the temperature and strain-rate dependence of the tensile properties, the following results were obtained:
    (1) The relation between σ and εp was well represented by the equation σ=Kεpm, where K is a constant and m is the strain hardening exponent. The value of m was measured to be 0.34 for vanadium and 0.11∼0.15 for V-H alloys at 293 K, which slightly increased with increase in test temperature up to 473 K for vanadium, but decreased for V-H alloys. This decrease of m for V-H alloys might involve the resolution of hydride: under the tensile test at a temperature where hydride is completely resolved into the matrix, the alloys show the same behavior as vanadium subjected to prestraining to a stress level equal to the yield stress of the alloys at the specified temperature; consequently the value of m for the alloys is smaller than that of vanadium. This fact was attributed to the dislocation structure which formed when the hydride was produced and still remained after the hydride was resolved; the existence of the structure was confirmed by electron microscopy in the dehydrogenated alloy. Hydride, if it exists in the alloys, contributes to the strengthening of the alloys but induces embrittlement.
    (2) The temperature and hydrogen concentration dependence of the tensile properties were also explained by consideration (1) mentioned above.
    (3) As the ductile-brittle transition temperature of the alloys was lower than the solvus temperature at which hydride precipitates, it was considered that the hydride itself contributed mainly to the embrittlement of the alloys.
    (4) Anomalous embrittlement of V-H alloys containing about 3000 wt ppm or more H was observed at 423 K, where all the hydrogen atoms should be in solution.
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  • 1977 Volume 41 Issue 12 Pages 1264
    Published: 1977
    Released: April 04, 2008
    Please see pdf. Wrong:[in Japanese], [in Japanese], [in Japanese], [in Japanese] Right:[in Japanese], [in Japanese], [in Japanese], [in Japanese]
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  • Shiomi Kikuchi, Toshio Tani, Masao Adachi
    1977 Volume 41 Issue 12 Pages 1265-1271
    Published: 1977
    Released: April 04, 2008
    Polycrystals of Cu-Sn solid solutions containing 1 to 4 at%Sn were deformed in tension at temperatures of 823, 873 and 923 K and at strain rates of 1.7×10−5∼8.3×10−4 s−1. The results obtained are as follows:
    (1) In the steady state deformation stage the strain rate is represented by the relation-ship of \dotε∝σn, where n=3.1∼3.7 in high tin content alloys and n=4.7∼5.7 in low tin content alloys. The steady state deformation behaviour changes from a pure metal type (n∼5) to an alloy type (n∼3) with increasing tin content.
    (2) In the high concentration alloys showing an alloy type behaviour a work softening phenomenon was always observed. The high temperature deformation in these alloys is controlled by the dragging of solute atomosphere for dislocation motion.
    (3) In the low concentration alloys showing a pure metal type behaviour, the parameter m*, the effective stress sensitivity of dislocation glide velocity, was found to be 1.0∼2.5. In many cases except the region of high strain rate, the dislocation motion is viscous.
    (4) The steady state strain rate is independent of the stacking fault energy when n∼3, but depends on it when n∼5.
    (5) In the case that the dislocation velocity is proportional to the effective stress the method of determining the internal stress by stress relaxation test was examined. The results obtained by this method was approximately in accord with those by the dip test using an extrapolation technique.
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  • Shiomi Kikuchi, Jun Shimizu, Hiroyuki Banba, Masao Adachi
    1977 Volume 41 Issue 12 Pages 1272-1277
    Published: 1977
    Released: April 04, 2008
    Copper-15 at%Al alloy single crystals oriented for a single slip system were deformed in tension at 973 K. The condition of steady state deformation was satisfied in stage I and stage III.
    The results obtained are as follows:
    (1) In stage I, the value of the stress exponent of steady state strain rate, n, is 3.0. The dislocation structure investigated by the etch pit technique is uniform. The relation between dislocation density and applied stress is given by the equation, τ=0.5μb\sqrtρ. The internal stress and effective stress are approximately proportional to the applied stress in this stage.
    (2) In stage III, the stress exponent, n, is 4.3. The dislocation structure is heterogeneous, forming two types of sub-boundaries which are perpendicular to the slip direction and slip plane, and is nearly parallel to the slip plane.
    (3) The average dislocation glide velocity is given by the equation, \barv=B*)m* where m*=0.9 in stage I and m*=1.3 in stage III. Therefore, the dislocation motion is viscous in both stages.
    (4) The difference in n value between the two stages is derived from the difference of the dislocation structures in the steady state deformation.
    (5) The rate process of Cu-Al solid solutions at high temperatures is the viscous glide motion of dislocation due to the solute atmosphere dragging.
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  • Hajime Suto, Mitsuhiko Yoshida
    1977 Volume 41 Issue 12 Pages 1278-1284
    Published: 1977
    Released: April 04, 2008
    Auger electron spectroscopy was employed to analyse the contents of C, P, Cr, Mn and Sn on the intergranular fracture surfaces of as-quenched plain carbon, 1%Mn-2.2%Cr and 12%Mn steels bearing 1%C. Results obtained are as follows:
    (1) Segregation of C to austenite and/or prior austenite grain boundaries increased rapidly with increasing bulk concentration of C up to 0.4% and saturated in steels containing C beyond 0.5%. The width of the C segregation zone was limited to few atomic-layers. Intergranular segregations of Cr and Mn were also observed.
    (2) Segregation of C to cementite/austenite (or/martensite) interfaces was enhanced by the enrichment of Cr in cementite.
    (3) The intergranular content of P or Sn was increased linearly with increasing P or Sn content in bulk, but no definite changes in segregation of other elements were observed.
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  • Keisuke Matsuura, Makoto Kitamura, Katsuya Watanabe
    1977 Volume 41 Issue 12 Pages 1285-1289
    Published: 1977
    Released: April 04, 2008
    The growth of coherent γ-iron precipitates in Cu-0.4%Fe and Cu-1.2%Fe alloys aged at 873 and 973 K was examined by transmission electron microscopy to evaluate the interface energy between copper and coherent γ-iron.
    The growth kinetics of γ-Fe particles could be described by the law of the Lifshitz-Wagner theory, \barRt1⁄3 (\barR: mean particle radius, t: ageing time), and the distribution of particle size was also in agreement with that expected from the above theory.
    The interface energy of coherent γ-iron in copper, which was evaluated from the growth rates of γ-iron particles based on the theory, increased with increasing volume fraction of particles. Furthermore, it was largely affected by a slight difference in the values of solubilities (equilibrium molar concentration of solute) as reported by some workers; it varied from about 0.25 to 0.35 J/m2 depending of the values of solubilities used. It was concluded by examing the methods used for determining the solubilities of iron in copper that the fomer value, 0.25±0.05 J/m2, was more reasonable for the interface energy of coherent γ-iron. The value was about one-half of the interface energy between copper and incoherent γ- or α-iron (about 0.52 J/m2), which was estimated from the dihedral angle of these incoherent particles existing in the grain boundaries of the matrix.
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  • Yasukiyo Ohtani, Jin-ichi Takamura, Nobutaka Narita, Tsutomu Haratani, ...
    1977 Volume 41 Issue 12 Pages 1290-1299
    Published: 1977
    Released: April 04, 2008
    The transition from stage I to II in the deformation of Cu, Cu-1 at%Ge, and Ag single crystals has experimentally been studied with particular attention to the formation of deformation bands (kink bands) through ‘bend gliding’. The bend gliding originates from the local inhomogeneity of primary main slip in a specimen deformed under the uniaxial tension, and the slip inhomogeneity is enhanced by the presence of grown-in sub-boundaries. It is shown that stage I terminates with the formation of kink bands through the stabilization process of the local bend-gliding regions. At the kink-band boundary dislocations are blocked from further movement and rapidly accumulated. Consequently the flow stress is increased and also secondary slip systems are activated by the stress concentration, resulting in a swift transition from stage I to II. The temperature dependence of the extent of stage I, which has generally been observed but not well understood, can also be interpreted in terms of the formation of dislocation walls or kink bands which becomes easier as the deformation temperature is raised. In this connection, a phenomenon named ‘annealing-hardening in pure metals’ found in stage I may provide evidence in support of this view.
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  • Takashi Nakamura, Kenji Morinaga, Tsutomu Yanagase
    1977 Volume 41 Issue 12 Pages 1300-1304
    Published: 1977
    Released: April 04, 2008
    The viscosity in the (alkali oxides and alkaline earth oxides)-SiO2-TiO2 system and in the PbO-SiO2-TiO2 system was measured by a crucible-rotating method. In the melts (RO, R2O):SiO2=7:6, the viscosity decreased with the addition of TiO2. The results of this viscosity and the electrical conductivity obtained in the previous work suggest that 4 co-ordinated Ti ions having the titanate anions are isolated, and will not link the silicate anions like Al2O3 in the silicate melts.
    In the PbO-SiO2-TiO2 system, when the molar ratio of PbO/SiO2=1, the viscosity also decreased with increasing TiO2, but it increased when PbO/SiO2=7⁄3. It may be considered that the Pb2+ ions which have a role of network modifier in silicate decrease and result in a higher polymerization state of silicate anions, as 4 co-ordinated Ti ions increase in the melt having the composition PbO/SiO2=7⁄3. The existence of 4 or 6 co-ordinated Ti ions in silicate glasses was determined by measurement of far-infrared spectra in the range of 20000∼70000 m−1.
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  • Setsuo Furihata, Kazuo Akashi, Jen-chi Huang, Shun-ichi Kurosawa
    1977 Volume 41 Issue 12 Pages 1305-1309
    Published: 1977
    Released: April 04, 2008
    The chronopotentiometry of K2TiF6 in a fused LiCl-KCl eutectic mixture was carried out by using a Pt microelectrode (0.8 mmφ), Pt/Pt2+ (0.009 mol/l) reference electrode and a counter electrode of high purity graphite for spectroscopy at 450°C, and the reduction waves of titanium ion were analyzed in detail.
    In the chronopotentiograms of titanium ion at a proper current density, three plateaus of potentials were apparently observed. It means that the reduction proceeds in three steps.
    Analysis of the chronopotentiogram of the first reduction wave, especially the relation between transition time and electrode potential, revealed that the first wave corresponds to the diffusion-controlled and reversible electrochemical reaction. The calculated electron number taking part in the first and second reactions, based on the chronopotentiogram, was about unitity, respectively, and the ratio of the transition time of the first reaction to that of the second reaction was about one-third. Therefore the first and second reductions seem to proceed according to Ti4++e\ ightleftharpoonsTi3+ and Ti3++e\ ightleftharpoonsTi2+, respectively.
    It is also shown that the third step reduction corresponds to an irreversible electrochemical reaction in which two electrons take part in the reaction.
    The estimated value of the diffusion coefficient of titanium ion (Ti4+) in the fused LiCl-KCl melt was about 9.01×10−4 cm2/sec at 450°C.
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  • Hisato Hagiwara, Harusige Tsubakino, Ryoichi Nozato
    1977 Volume 41 Issue 12 Pages 1310-1316
    Published: 1977
    Released: April 04, 2008
    Discontinuous precipitation in Cu-2.1 wt%Be alloy has been investigated by means of metallographic observations and microhardness measurements. The variation in volume fraction of discontinuous precipitation cells and cell radius with ageing time, and number of cells per unit volume have been determined by quantitative metallographic measurements in the specimens aged at temperatures from 473 to 773 K.
    Upon ageing above 623 K, the growth rate (G) of cells decreases and the interlamellar spacing (l) in cells increases with ageing time progressively after the linear growth rate of cells. These phenomena may be attributed to the influence of continuous precipitates (plate-like γ′ precipitates), which take place in grain center regions where cells have not proceeded, on the cell growth. Below 573 K, continuous precipitates (fine γ′ precipitates) form prior to the discontinuous precipitation but the variation in G and l with ageing time is not observed.
    Volume fraction of discontinuous precipitation cells, f, can be represented by Johnson-Mehl’s equation: f=1−exp(−btn), where t is the ageing time and b and n are constants, and 2.2 above 623 K and 1.4 below 573 K are obtained as n’s values in the range of ageing times that G’s are linear. Above 623 K, the nucleation sites of cells are considered to be grain boundary edges according to Cahn’s theory. The number of cells is larger by several times in the n=1.4 regions than the 2.2 regions. These phenomena may be attributed to the influence of the elastic strain resulting from the formation of the G.P. zones and fine γ′ precipitates prior to the discontinuous precipitation upon cell nucleation.
    From the dependence of the linear growth rate of cells on the ageing temperature, 115 kJ/mol is obtained as the apparent activation energy for cell growth.
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